Hot Shirts Men's Mustang/ Flex Fit Hat Officially licensed Hats are top quality embroidered - popularlow profile flex-fit style hat featuring cotton/twill front panels and bill and stylish polyester mesh back. Sizing (approximate): S/M is approximately 22 inches relaxed. Hat flex/adjusts up to about 22-3/4 inches. L/XL is approximately 22-3/4 inches relaxed. Hat flex/adjusts up to about 23-1/2 inches.